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A boil or furuncle is a skin infection caused by the bacteria Staphylococcus aureus. It tends to thrive in warm, moist areas of skin, most commonly the nostrils, armpits, the crease between the buttocks, and the inner thighs.
Boils can also spread under the skin and cluster. If this happens, the clusters form deeper abscesses called carbuncles, which may scar the skin.
The size and color of a boil can vary, depending on how severe it is, or the amount of skin involved. However, most boils tend to have a similar appearance.
Fast facts about boils
Fast facts about boils on the inner thigh:
- Normally, boils are not a cause for concern and do not require medical attention.
- It is usually not safe to drain boils at home.
- There are many ways to prevent boils from forming on the inner thigh.
Boils occur when the bacteria Staphyloccus auerus invades the walls of a damaged or exposed hair follicle and colonizes it, causing infection.
Some 10 to 20 percent of the population are carriers of Staphyloccus auerus. Being a carrier means that the bacteria normally lives on the surface of a person’s skin.
Carriers, and people with boils, can spread the bacteria through skin-to-skin contact. The bacteria can also spread through contact with contaminated objects, such as towels and sheets. In most people, infections only occur when the skin’s natural barrier is broken or compromised by factors such as injury or friction.
Anyone of any age can develop boils. They commonly appear in areas of the body prone to chafing, particularly the inner thighs.
Certain factors are known to increase the likelihood of developing the condition.
Common risk factors for boils include:
- contact with someone infected with Staphyloccus aureus
- nicks or cuts in the skin
- living or working in a crowded area
- immune conditions
- being over the age of 65
- poor hygiene
- animal scratches or bites
- iron deficiencies
- poor nutrition or diet
- lack of exercise
- prior use of antibiotics, especially multiple or improper usage in the past 6 months
- other skin infections or conditions, such as psoriasis and eczema
- long-term use of steroids or corticosteroids
- intravenous drug use
- extreme or chronic stress
Specific factors may contribute to a high risk of developing boils on the inner thigh. These include:
- wearing loose or ill-fitting clothing while exercising
- playing sports or doing exercises that cause chafing of the inner thighs, such as running, long-distance walking, hiking, or biking
- wearing dirty clothing, particularly when exercising or engaging in activities that involve inner-thigh friction or sweating
- walking or running in warm, humid climates
- shaving, waxing, and other means of hair removal that break the surface of the skin
While symptoms may vary in severity, most boils:
- are round, red, swollen bumps that grow gradually
- are tender and sensitive, sometimes even to air
- eventually discharge a whitish-colored pus made up of dead tissue and blood cells
- last for around 10 days
Boils may appear alone or as a group. Boils that form a group or cluster are collectively called a carbuncle.
Boils can appear anywhere on the body, including the inner thigh.
Some boils require medical attention. Consult a doctor about boils that:
- appear on the face or upper neck
- do not rupture within about 10 days of forming
- will not fully drain
- do not fully heal within 1 to 3 weeks of rupturing
- are very painful and do not respond to over-the-counter anti-inflammatory or pain medications
- become more painful and swollen after rupturing
- seem to be spreading to new tissues
- feel soft and spongy
- leak pus from more than one location
- are larger than 5 millimeters
- include more than one head or point
- are clustered or blistering
- have drainage or fluid that is not white or clear
- are surrounded by a patch of skin that is painful, abnormal in color, or otherwise looks unhealthy
A person should also see a doctor if a boil appears at the same time as any of the following symptoms:
- nausea, vomiting, loss of appetite, or unexplained weight loss
- fever, chills, or other flu-like symptoms
- unexplained or abnormal bruising
Some individuals have a higher risk of complications from boils and are more likely to require medical attention.
People who have the following conditions should consider talking with a doctor about their boils:
- immune conditions
- people at risk for endocarditis, such as those with congenital or developed heart conditions
- conditions that require management that weakens the immune system, such as chemotherapy
In most cases, the first line of treatment is to clean the abscess and surrounding skin with warm, soapy water. Avoid touching, rubbing, or applying pressure to a boil that has just been cleaned.
There are ways to draw the pus to the surface of the boil. This increases pressure in the abscess, making the boil more likely to rupture.
One of the easiest ways to safely drain a boil at home is to dip a clean facecloth or towel in very warm water and gently hold it against the boil.
Ideally, this compress should be as warm as possible without burning the skin. The towel or cloth should be held in place until it becomes cool or room temperature. It will often take several sessions for the boil to burst. Hot compresses are also available to buy in pharmacies and online.
The following tips can help when dealing with boils at home:
- Never force a boil to rupture by squeezing or piercing it.
- Keep a healing boil clean.
- Avoid touching, picking, or placing unnecessary pressure on a boil.
- Gently apply over-the-counter antiseptic and antibiotic creams and liquids.
- Cover a healing boil with gauze or a sterile bandage.
- Avoid activities that cause friction between the inner thighs.
- Take over-the-counter anti-inflammatories.
- Wash the hands with soap and water or use sanitizer after touching a boil.
- Wipe the surrounding skin daily for 1 week with a mixture of 70 percent isopropyl alcohol and 30 percent water.
- Encourage others in the household to practice similar precautions.
- Regularly replace personal hygiene products that can cause cuts and scrapes, particularly razor blades.
- For chronic or severe infections, wash every product that comes into contact with the body daily.
A doctor may need to cut into a boil to drain it. This may be necessary if a boil is severe, very large, or if it will not drain on its own. Incising might also be needed in cases of chronic boils.
A doctor may also prescribe oral antibiotics to clear the infection. When boils are chronic or do not respond to oral medication alone, a doctor may prescribe topical antibiotic creams or antibiotic nasal sprays.
The following tips can reduce the risk of developing boils:
- Use products designed to prevent chafing when playing sports or exercising.
- Modify these activities to lessen chafing.
- Wash the entire body with soap and water daily.
- Wash the hands regularly.
- Avoid picking the nose.
- Change and wash linens regularly.
- Wear properly fitting, clean clothing while exercising.
- Do not share towels, underwear, or sheets with other people, including family members.
- Eat a balanced, nutritious diet.
- Exercise regularly.
- Avoid or stop smoking.
- Maintain a healthy body weight.
- Consume a healthy amount of iron, through diet or supplements.
- Have a daily vitamin C intake of 1,000 micrograms.
- Never share personal hygiene products, especially those capable of breaking the skin’s surface, such as razors.
- Be careful not to cut the skin.
- Exfoliate skin that has had hair removed every few days.
Boils or furuncles are a common type of skin abscess. Most rupture within 10 days of forming, and after a boil drains, it tends to heal within 1 to 3 weeks.
In some cases, boils can lead to complications, including scarring and painful clustering deep beneath the skin’s surface. These clusters of boils are called carbuncles.
If left untreated, severe boils or carbuncles can lead to life-threatening conditions. These may include systemic infections, which can compromise the bloodstream or the entire body.
Talk with a doctor about boils that do not heal on their own, are very large, or are complicated by additional symptoms or conditions.